We will continue our studies on the regulation of glycogen metabolism in liver as follows: (a) Purification, structural analysis and the study of the regulation of phosphorylase kinase and (b) A study of the substrate specificities and role of the protein phosphatases in the regulation of liver glycogen metabolism. Our second project will be to isolate and characterize the protein or proteins that are covalently bound to native liver glycogen and which act as acceptors for glucose units transferred from UDPglucose in in vitro experiments. The chemical nature of the carbohydrate-protein bond will be determined and the nature of the enzymes involved constructing the carbohydrate moiety of the complex will be explored.